space

Distributes an input signal among 4 channels using cartesian coordinates.

It uses Cartesian xy coordinates to calculate the balance of the outputs. The xy coordinates can be defined in a separate text file and accessed through a Function statement in the score using Gen28, or they can be specified using the optional kx, ky arguments. The advantages to the former are:

1. A graphic user interface can be used to draw and edit the trajectory through the Cartesian plane
2. The file format is in the form time1 X1 Y1 time2 X2 Y2 time3 X3 Y3 allowing the user to define a time-tagged trajectory

space then allows the user to specify a time pointer (much as is used for pvoc, lpread and some other units) to have detailed control over the final speed of movement.

Syntax

a1, a2, a3, a4  space asig, ifn, ktime, kreverbsend, kx, ky

Initialization

ifn -- number of the stored function created using Gen28. This function generator reads a text file which contains sets of three values representing the xy coordinates and a time-tag for when the signal should be placed at that location. The file should look like:

0       -1       1
1        1       1
2        4       4
2.1     -4      -4
3       10     -10
5      -40       0

If that file were named “move” then the Gen28 call in the score would like:

f1 0 0 28 "move"

Gen28 takes 0 as the size and automatically allocates memory. It creates values to 10 milliseconds of resolution. So in this case there will be 500 values created by interpolating X1 to X2 to X3 and so on, and Y1 to Y2 to Y3 and so on, over the appropriate number of values that are stored in the function table. In the above example, the sound will begin in the left front, over 1 second it will move to the right front, over another second it move further into the distance but still in the right front, then in just 1/10th of a second it moves to the left rear, a bit distant. Finally over the last .9 seconds the sound will move to the right rear, moderately distant, and it comes to rest between the two left channels (due west!), quite distant. Since the values in the table are accessed through the use of a time-pointer in the space unit, the actual timing can be made to follow the file's timing exactly or it can be made to go faster or slower through the same trajectory. If you have access to the GUI that allows one to draw and edit the files, there is no need to create the text files manually. But as long as the file is ASCII and in the format shown above, it doesn't matter how it is made!

Important

If ifn is 0, then space will take its values for the xy coordinates from kx and ky.

Performance

The configuration of the xy coordinates in space places the signal in the following way:

• a1 is -1, 1
• a2 is 1, 1
• a3 is -1, -1
• a4 is 1, -1

This assumes a loudspeaker set up as a1 is left front, a2 is right front, a3 is left back, a4 is right back. Values greater than 1 will result in sounds being attenuated, as if in the distance. space considers the speakers to be at a distance of 1; smaller values of xy can be used, but space will not amplify the signal in this case. It will, however balance the signal so that it can sound as if it were within the 4 speaker space. x=0, y=1, will place the signal equally balanced between left and right front channels, x=y=0 will place the signal equally in all 4 channels, and so on. Although there must be 4 output signals from space, it can be used in a 2 channel orchestra. If the xy's are kept so that y>=1, it should work well to do panning and fixed localization in a stereo field.

asig -- input audio signal.

ktime -- index into the table containing the xy coordinates. If used like:

ktime           line  0, 5, 5
a1, a2, a3, a4  space asig, 1, ktime, ...

with the file “move” described above, the speed of the signal's movement will be exactly as described in that file. However:

ktime           line  0, 10, 5

the signal will move at half the speed specified. Or in the case of:

ktime           line  5, 15, 0

the signal will move in the reverse direction as specified and 3 times slower! Finally:

ktime           line  2, 10, 3

will cause the signal to move only from the place specified in line 3 of the text file to the place specified in line 5 of the text file, and it will take 10 seconds to do it.

kreverbsend -- the percentage of the direct signal that will be factored along with the distance as derived from the xy coordinates to calculate signal amounts that can be sent to reverb units such as reverb, or reverb2.

kx, ky -- when ifn is 0, space and spdist will use these values as the xy coordinates to localize the signal.

Examples

Here is an example of the space opcode. It uses the file space_quad.csd.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac   ;;;realtime audio out
;-iadc    ;;;uncomment -iadc if realtime audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o space_quad.wav -W ;;; for file output any platform
</CsOptions> 
<CsInstruments>

sr = 44100 
ksmps = 32 
0dbfs  = 1 
nchnls = 4

ga1     init    0
ga2     init    0
ga3     init    0
ga4     init    0

instr 1 ;uses GEN28 file "move", as found in /manual/examples

kx    init 0
ky    init 0
ktime line  0, 5, 5                             ;same time as in table 1 (="move")
asig  diskin2 "drumsMlp.wav", 1, 0, 1           ;sound source is looped
a1, a2, a3, a4 space asig, 1, ktime, .1, kx, ky ;use table 1 = GEN28
ar1, ar2, ar3, ar4 spsend                       ;send to reverb

ga1  = ga1+ar1
ga2  = ga2+ar2
ga3  = ga3+ar3
ga4  = ga4+ar4
     outq a1, a2, a3, a4

endin

instr 99 ; reverb instrument

a1 reverb2 ga1, 2.5, .5
a2 reverb2 ga2, 2.5, .5
a3 reverb2 ga3, 2.5, .5
a4 reverb2 ga4, 2.5, .5
   outq a1, a2, a3, a4

ga1=0   
ga2=0
ga3=0
ga4=0

endin
</CsInstruments>
<CsScore>
f1 0 0 28 "move"

i1 0 5          ;same time as ktime
i 99 0 10       ;keep reverb active
e
</CsScore>
</CsoundSynthesizer>

In the above example, the signal, asig, is moved according to the data in Function #1 indexed by ktime. space sends the appropriate amount of the signal internally to spsend. The outputs of the spsend are added to global accumulators in a common Csound style and the global signals are used as inputs to the reverb units in a separate instrument.

space can be useful for quad and stereo panning as well as fixed placed of sounds anywhere between two loudspeakers. Below is an example of the fixed placement of sounds in a stereo field using xy values from the score instead of a function table. It uses the file space_stereo.csd.

<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac   ;;;realtime audio out
;-iadc    ;;;uncomment -iadc if realtime audio input is needed too
; For Non-realtime ouput leave only the line below:
; -o space_stereo.wav -W ;;; for file output any platform
</CsOptions> 
<CsInstruments>

sr = 44100 
ksmps = 32 
0dbfs  = 1 
nchnls = 2

ga1 init 0
ga2 init 0

instr 1

kx   = p4
ky   = p5
asig diskin2 "drumsMlp.wav", 1
a1, a2, a3, a4 space asig, 0, 0, .1, kx, ky     ;take position values from p4, p5
ar1, ar2, ar3, ar4 spsend                       ;send to reverb

ga1 = ga1+ar1
ga2 = ga2+ar2
    outs a1, a2

endin

instr 99 ; reverb instrument

a1 reverb2 ga1, 2.5, .5
a2 reverb2 ga2, 2.5, .5
   outs a1, a2

ga1=0
ga2=0

endin

</CsInstruments>
<CsScore>
;place the sound in the left speaker and near
i1 0 1 -1 1
;place the sound in the right speaker and far
i1 1 1 45 45
;place the sound equally between left and right and in the middle ground distance
i1 2 1 0 12

i 99 0 7        ;keep reverb active
e
</CsScore>
</CsoundSynthesizer>

spdist demonstrates an example of a simple intuitive use of the distance values to simulate Doppler shift.

See also

Panning and Spatialization: Amplitude spatialization

Credits

Author: Richard Karpen
Seattle, WA USA
1998

New in Csound version 3.48